Dam Construction Research Articles

Seepage handling using secant pile as a solution to replace curtain grouting and dam stability evaluation to optimize work on the Margatiga Dam construction project

Based on the results of a soil investigation using the bore log method carried out by the Consultant, it was found that the foundations of the spillway building and intake building are in a geological condition that is composed predominantly of sand and porous deposits or easily absorbs water, as well as rocks with the characteristics of fine tuff rock, indicating that the foundation The building is prone to seepage. The seepage treatment contained in the contract is the curtain grouting method 20 meters deep with a distance of 2 meters between points. It is necessary to carry out trial grouting in 3 location zones to be sure. Therefore, it is necessary to analyze the secant pile design. In the work on filling the dam body on the left and right sides, a review needs to be carried out to optimize the implementation of the work because it has a safety factor that is too high than the required safety factor. Secant pile design planning and cross-section evaluation calculations use software to help calculate seepage and stability analysis. Based on the results of modeling analysis calculations and evaluation of cost and implementation time calculations that meet the criteria, it is recommended to handle seepage using secant piles, namely with dimensions of 80 cm, overlap of 15 cm and a depth of up to -10 elevation and recommendations for the cross-section of the dam body, namely by modifying the slope of the section.

Dynamic mechanism of check dams on evolution of river corridors based on UAV telemetry combined with numerical simulations

AbstractCheck dams are a critical soil and water conservation engineering measure in gullies that significantly influence erosion, transportation, and sediment accumulation. Check dams help reduce erosion in the upstream area, ignoring the off‐site erosion reduction capacity due to erosion dynamics, and it also alters the morphology of gullies. The morphology of the gully cross‐section from the head to the inlet of the gully is mainly “V” shaped, “V, U,” transitional shaped, “U” shaped and trapezoidal shaped. The construction of check dams can force the geomorphologic evolution of the sub‐watershed to accelerate the transition to “old age” and reduce the allocation of sediment initiation during field sub‐flooding, thus promoting sediment deposition processes. The percentage of downstream scour hours in watersheds where check dams were constructed was 0.65% and 0.80%, respectively, compared to 19.78% and 19.06% in watersheds where there are no check dams. The results reveal the role check dam constructions play in gully morphology evolution from a hydrodynamic perspective and fill the gaps in off‐site erosion reduction, providing theoretical support for assessing the role of check dams in soil and water conservation work.

Time traveling through the floodscape: assessing the spatial and temporal probability of floods and susceptibility zones in the Lower Damodar Basin.

The flood of Damodar river is a well-known fact which is used to the whole riverine society of the basin as well as to the eastern India. The study aims to estimate the spatio-temporal probability of floods and identify susceptible zones in the Lower Damodar Basin (LDB). A flood frequency analysis around 90years hydrological series is performed using the Log-Pearson Type III model. The frequency ratio model has also been applied to determine the spatial context of flood. This reveals the extent to which the LDB could be inundated in response to peak discharge conditions, especially during the monsoon season. The findings indicate that 36.64% of the LDB falls under high to very high flood susceptibility categories, revealing an increasing downstream flood vulnerability trend. Hydro-geomorphic factors substantially contribute to the susceptibility of the LDB to high magnitude floods. A significant shift in flood recurrence intervals, from biennial occurrences in the pre-dam period to decadal or vicennial occurrences in the post-dam period, is observed. Despite a reduction in high-magnitude flood incidents due to dam and barrage construction, irregular flood events persist. The effect of flood in the LDB region is considered to be either positive as well as negative in terms of wholistic sense and impact. The analytical results of this research could serve to identify flood-prone zones and guide the development of flood resilience policies, thereby promoting sustainability within the LDB floodplain.

An explainable integrated machine learning model for mapping soil erosion by wind and water in a catchment with three desiccated lakes

Soil erosion by water and wind is a critical challenge for sustainable management of catchments in drylands and accurate spatial information can help in mitigation of its destructive consequences. Here, seven machine learning (ML) models were applied to map simultaneously the water and wind erosions in the Bakhtegan catchment, south Iran, with three dried lakes in its southern part and three dams established in upstream parts of the lakes. The analysis identified 10 and 11 effective variables controlling water and wind erosions, among 20 and 17 potential variables, respectively, via the MARS feature selection algorithm. According to the most accurate ML models (artificial neural network for water erosion, and Cubist for wind erosion), an integrated model was developed to map soil erosion by water and wind simultaneously. Permutation feature importance (PFI) and Shapley additive exPlanation (SHAP) interpretation techniques were employed to explain the model outputs, revealing that 19.7 % of the total area belonged to high and very high susceptibility classes to soil erosion by water and wind. The PFI plot revealed that the slope and wind speed were the most influencing factors for water and wind erosion, respectively. According to SHAP decision plot, slope had the highest contribution on the predictive water erosion model’s output, whereas vegetation cover exhibited the highest contribution on the predictive wind erosion model’s output. Due to climate change and intensified drought during the recent years, as well as due to construction of dams upstream of the lakes, the southern part of the study area was converted to a source of sand and dust storms. The hotspots with severe water erosion are distributed all over the study area, rendering it quite vulnerable to adverse climate change projections.

Age and crack length effects on fracture parameters of dam gallery concrete: Experimental investigation and modeling

Cracks of varying lengths may occur in galleries throughout dam construction, operation, and management processes. This study investigates the influence of age and crack length on the fracture parameters of gallery concrete, which is crucial for understanding the mechanisms and risks associated with gallery cracking and for developing appropriate treatment measures. Wedge-splitting tests were performed on gallery concrete specimens with varying crack lengths and at different ages. It was found that the fracture parameters measured at different ages all decrease with the increase of crack length. Based on the test results, size-independent material constants such as fracture toughness and the effective length of the fracture process zone were derived and modeled using an exponential function to reflect their time-varying characteristics. A fracture model was proposed and validated, which can accurately predict the fracture behavior of gallery concrete across varying ages and crack lengths, and is applicable in practical dam gallery crack analysis for assessing crack stability and evaluating the effectiveness of treatment measures.

Reducing climate impacts on karst groundwater resources by constructing a cave dam. A case study from Central Taurus Karst, Türkiye

Susuz karst aquifer is a mountainous and highly karstified aquifer located at the Central Taurus karst belt, Seydişehir, Türkiye. Pınarbaşı karst spring is a major water resource of the Susuz karst aquifer which drains approximately 15 million m3 of water annually, mostly between January and July. As the Pınarbaşı spring dries up for the rest of the year, local water needs frequently emerge during the dry periods, especially for animal livestock and domestic usage. However, one major problem in the karst region is the decreasing trend in the spring discharge rate and increasing length of the dry period due to the impact of climate change. For this reason, to reduce the climate impact on the karst aquifer it is essential to explore alternative engineering solutions where they are applicable. This study proposes the construction of a cave dam in the Susuz karst system to retain and store groundwater during the dry period. Based on the accumulated hydrogeological knowledge and experiences in the karst region, we first conceptualized the cave dam construction and then indicated the positive influence of the stored groundwater under changing climate considering two main climate scenarios (SSP245 and SSP585). Our findings indicate that the (proposed) cave dam potentially stores 4 million m3 of water, which represents nearly 35 % of the mean annual spring discharge under current climate conditions. This amount is expected to rise over 50 % of the total discharge in future climate conditions.

Evaluation of water shortage and instream flows of shared rivers in South Korea according to the dam operations in North Korea

Abstract The Korean Peninsula's mountainous terrain poses challenges to effective water resource management. Notably, two significant river basins, North Han River and Imjin River basins, are essentially shared rivers originating in North Korea. After the construction of various dams in North Korea, billions of tons per year of water annually decreased from the upper reaches of these rivers of North Korea to South Korea. This study conducted an impact analysis on two major river basins affected by dam operations in North Korea. Both before and after the Imnam Dam operation, significant reduction (27.7%) in the average monthly inflow was observed, and the total release of the Hwacheon Dam in South Korea decreased by 40.2%. The analysis of instream flow indicated that the operation of dams in North Korea had a substantial impact on fulfilling instream flow requirements for dams located in North Han River and Imjin River basins. To ensure instream flow, this study proposed two plans. The first plan involved the utilization of existing dams in the North Han River basin, while the second plan suggested connecting the dams in North Korea, taking into account the shared rivers.

Advancing Environmental Flows Science: Hindcasting and Forecasting Flow–Ecology Relationships

To advance current environmental flow standards in Texas, we developed field, laboratory, and analytical methods to model recruitment dynamics of indicator species selected to cover a range of population responses to flow variation. Preliminary investigations were conducted in three central Texas river basins to evaluate the feasibility of these methods for formulating and evaluating the state's environmental flow standards. Age analysis allowed back‐calculation of dates of fish hatching, mussel recruitment, and tree germination for estimation of temporal variation in recruitment. Recruitment data were then analyzed in relation to flow regime components. Statistical models were derived for flow–recruitment relationships of Shoal Chub Macrhybopsis hyostoma, Smallmouth Buffalo Ictiobus bubalus, threeridge mussel Amblema plicata, and boxelder Acer negundo. The Shoal Chub model was used to hindcast recruitment dynamics in the Brazos River, revealing a decline in recruitment after dam construction. The Smallmouth Buffalo model revealed that strong year‐classes were positively associated with springtime pulses of long duration but negatively associated with frequent short‐duration pulses. Results for the threeridge mussel were not as easily interpreted, but for all three river basins generally showed weaker recruitment during periods with extreme low and high flows. The boxelder model revealed positive associations between recruitment and high flow components and was used to forecast the probability of germination under five simulated flow regime scenarios, thereby providing an additional means for evaluating the suitability of environmental flow standards. Assessment of how hydrology influences recruitment provides an evidence‐based method to hindcast responses to past flow regimes and forecast responses to future flow scenarios, thereby providing a basis for evaluating environmental flow standards and water management options.

Population assignment of migratory Westslope Cutthroat Trout (WCT) in the Clark Fork–Pend Oreille River basin

AbstractObjectiveThe Clark Fork–Pend Oreille River basin of northeastern Washington and the Idaho Panhandle historically supported a robust metapopulation of the Westslope Cutthroat Trout (WCT) Oncorhynchus lewisi, a western native salmonid of high cultural and economic value. The construction of impassible hydroelectric dams and smaller instream barriers has prevented the return of migratory WCT to spawning tributaries, leading to the fragmentation of this metapopulation over the past 100 years. One such impassible barrier is Albeni Falls Dam (AFD) near Newport, Washington, which was completed without fish passage capabilities in 1955. We sought to examine large‐scale genetic patterns in the study area and determine the most likely spawning tributary of origin for migratory WCT captured below AFD.MethodsWe created a genetic baseline representative of populations within the Clark Fork–Pend Oreille River basin from upstream and downstream of the dam using 191 biallelic single‐nucleotide polymorphism genetic markers. Our data set included 124 collections, which allowed for an examination of population structure and hatchery influence across the study area and provided a robust tool for population assignment. Population assignment tests were conducted using the program RUBIAS.ResultPopulation assignment tests were successful for all pure WCT of unknown origin despite potential influence from hatchery lineages across the study area. Of 83 migratory WCT captured below AFD, approximately 80% were assigned to tributaries upstream of AFD with a posterior assignment probability of at least 90%. Only one fish was assigned to a tributary downstream of AFD.ConclusionOur results indicate that AFD disrupts the natural metapopulation dynamics of WCT populations in the basin. Passage for WCT at this barrier would reestablish metapopulation connectivity within the basin by allowing migratory individuals to make genetic contributions to populations upstream of the dam.

Temporal Changes in Water and Sediment Discharges: Impacts of Climate Change and Human Activities in the Red River Basin (1958–2021) with Projections up to 2100

The present study examined temporal variations in water and sediment discharges in the Red River basin from 1958 to 2021 resulting from climate change and anthropogenic factors, with projections extended to 2100. The 64-year observational period was divided into five distinct stages: 1958–1971 (Stage I: natural conditions); 1972–1988 (Stage II: onset of human activities); 1989–2010 (Stage III: post Hoa Binh dam construction); 2011–2016 (Stage IV: series of new dam constructions); and 2017–2021 (Stage V: combined effects of human activities and climate change). Attribution analysis revealed that human activities accounted for 62% and 92% of the dramatic declines in sediment loads in Stages III and IV, respectively. Projection results of fluvial sediment loads over an approximate 150-year timeframe (1958–2100) indicate an overriding impact from human activities. Climate change projections based on four scenarios (−5%, +5%, +10%, and +15% change per year) suggest associated decreases or increases in river flows. This study predicts that projected 21st century increases in river flow attributable to climate change will offset up to eight percent of the human-induced sediment load deficit.

The lake and groundwater interaction based on water balance in Dongting Lake, China

Study region: Dongting Lake (DTL), the second largest freshwater lake in China, plays a crucial role in regulating and storing water within the Yangtze River Basin.Study focus: The study utilized the water balance method to extensively investigate the exchange volume of groundwater and DTL from 2003 to 2020. Furthermore, we analyzed the impact of climate change and human activities on the interaction between groundwater and DTL.New hydrological insights for the region: Unlike previous studies, our study further included the ungauged runoff, providing a more comprehensive assessment of the water balance of DTL. From May to July, groundwater recharge from DTL, with an average monthly recharge of 0.71 km³. Conversely, groundwater discharges into DTL from August to April of the following year, with an average monthly discharge of 1.12 km³. The net groundwater discharge into the lake from 2003 to 2020 amounts to 7.98 km³/yr. Intriguingly, precipitation over the lake contributes a mere 0.6% to the total inflow, while lake evapotranspiration constitutes only 0.4% of the total outflow. Inflow runoff and outflow runoff play a leading role in the water balance of DTL, significantly influencing the exchange capacity between the lake and groundwater. Groundwater discharge into the lake serves as compensation for diminished runoff stemming from extreme climate occurrences, like droughts, and anthropogenic actions such as dam construction.

Study of the Risks of Overflow and Salinization of the Mbao Backwater: Impact on Local Populations

The Mbao backwater, located in the Mbao forest in Dakar, plays an important role in income generation and flood prevention for the localities of Pikine, Keur Massar and Rufisque. Today, it is increasingly threatened with the risk of overflow due to the considerable reduction in its storage capacity and the arrival of large quantities of runoff water from the watersheds of which it is the outlet. In addition, its salinization is noted due to its proximity to the sea. The objective of this article is to present the results of the study of the risks of overflow and salinization of the Mbao backwater and their impacts on socio-economic activities. After modelling the volumes of water received by the backwater using the EPASWMM software and a study of its vulnerability to saline intrusion during high tides, It emerged that in the event of a decadal rainfall of the Desbordes type in the area, an overflow of 1,001,758 m3 could be noted, causing flooding and inconvenience to the local populations. In addition, a connection between the waters of the sea and those of the backwater causes salinization of the latter, negatively impacting the market gardening activities carried out by local residents. A pumping system at 1,500 m3/h could help prevent the backwater from overflowing, and the construction of a weir dam between the sea and the backwater would help control the salinization of the downstream part. Keywords: risk, overflow, salinization, vulnerability, Mbao backwater

China Southern Power Grid’s decarbonization likely to impact cropland and transboundary rivers

Decarbonizing the electricity sector requires massive investments in generation and transmission infrastructures that may impact both water and land resources. Characterizing these effects is key to ensure a sustainable energy transition. Here, we identify and quantify the unintended consequences of decarbonizing the China Southern Power Grid, China’s second-largest grid. We show that reaching carbon neutrality by 2060 is feasible; yet, doing so requires converting 40,000 square kilometers of land to support solar and wind as well as tapping on rivers to build ~32 gigawatts of hydropower. The impact of wind and solar development would span across multiple sectors, since crop and grassland constitute 90% of the identified sites. The construction of new dams may carry major externalities and trickle down to nearby countries, as most dams are located in transboundary rivers. Curbing the international footprint of this decarbonization effort would require additional investments (~12 billion United States dollars) in carbon capture technologies.

Gravitational Failure Occurrence and Evolution of Rock Slopes Due to Dam Construction: A Case Study of Three Reservoirs in Southwest China

Gravitational Failure Occurrence and Evolution of Rock Slopes Due to Dam Construction: A Case Study of Three Reservoirs in Southwest China

Hydropower Politics in Northeast India: Dam Development Contestations, Electoral Politics and Power Reconfigurations in Sikkim

Around the world, the development of large dams has been increasingly contested. India is no exception and has seen the mobilisation of powerful domestic and transnational socio-environmental movements against dams over more than four decades. In this context, the State of Sikkim in northeast India has been entangled in prolonged hydropower development conflicts since the late 1990s. This article analyses these conflictive entanglements between the Government of India, the State Government of Sikkim, power companies and Sikkim’s autochthonous tribe, the Lepchas. It zooms in on the period of 2011–2017, which saw an abrupt escalation of the conflicts to analyse the messy, deeply political and often unpredictable and contradictory world of dam construction and its contestations. Our analysis is informed by the power cube framework developed by John Gaventa. Our analysis shows how hydropower development is deeply intertwined with local patronage relationships. We show how local elections bring out dam conflict and the operation of power into the open, sometimes leading to abrupt and unexpected switches in positions in relation to hydropower development. We show that these switches should be seen not only as “strategic electoral tactics” but also and importantly as contentious political struggles that (re)configure power in the region. We show how in this process, powerful political actors continuously seek to stabilise power relations among the governing and the governed, choreographing a specific socio-hydraulic order that stretches way beyond simple pro- and anti-dam actors and coalitions as it is embedded in deep hydro(-electro) politics and power plays.

Mechanical Characteristics of Tailings in Different Depositional Zones: A Case Study of Caijiagou Tailings Pond in Shaanxi, China

This study examines the widespread practice of upstream tailings dam construction in metallurgical mines in China, conducting comprehensive testing and research on tailings from various depositional zones of the Caijiagou tailings pond. Analysis of the test results from three types of tailings reveals a systematic relationship between the mechanical characteristics of tailings and their depositional zones: the farther from the dam, the finer the tailings particles, categorized as silty clay tailing, silt tailing, and sandy silt tailing. Consistent patterns were observed in the consolidated-drained shear strength and consolidated-undrained effective shear strength of these tailings. Among these, sandy silt tailing exhibited the highest strength, whereas silty clay tailing displayed the lowest. The dynamic stress–strain relationships of all three tailings types are described using the Hardin equivalent viscous-elastic model, where the initial dynamic shear modulus and the maximum dynamic shear stress in the model increased with effective confining pressure. The damping ratios exhibited a three-stage trend with increasing dynamic strain: gradual increase, rapid growth, and then gradual stabilization. Under various consolidated stress conditions, the ratio of the damping ratio to the maximum damping ratio versus the reduction in dynamic shear modulus showed a favorable linear relationship. Under vibration conditions, the dynamic shear stress corresponding to tailings failure increased with higher effective confining pressure and consolidated stress ratio. Finally, this study summarizes the parameters and indicators related to the saturated tailings of iron mines used in the research. Our work provides a foundation and reference for the design of tailings dams and the development and utilization of abandoned tailings ponds.

Impact of dam construction on sediment transport capacity: A case study of the Three Gorges Reservoir

AbstractReservoir sedimentation affects lifespan, hydropower generation, water resource use, and ecosystem sustainability. In this study, using measured data from the world‐renowned Three Gorges Reservoir (TGR), sediment transport capacity was analysed from 2002 to 2020 at four TGR gauging stations (Cuntan, Qingxichang, Wanxian, and Miaohe). The result indicated that: (1) a significant decrease in sediment transport capacity occurred in the TGR before and after dam construction, with an overall reduction of 82% in the perennial backwater zone. Notably, Qingxichang, Wanxian, and Miaohe experienced reductions of 40%, 91%, and 59%, respectively. Since the initial operation phase, their maximum monthly sediment transport capacity has consistently occurred in July. (2) Changes in the water level in front of the dam, the incoming flow, and sediment influxes were the primary factors driving the annual variations in sediment transport capacity. Among the factors affecting the variation of sediment transport capacity along the TGR, the influence of the cross‐sectional morphology was more pronounced than that of the distance from the dam. Sediment transport capacities in the wide and shallow sections were considerably lower than those in the narrow and deep sections. (3) A sediment transport amplitude index () was proposed to assess the sediment dynamics within the TGR, which effectively characterized the sedimentation conditions based on the relative importance of these influencing factors. These findings provide a theoretical basis for operational strategies in the TGR and offer insights into the patterns of sediment transport capacity changes in reservoir areas before and after dam construction in other river‐type reservoirs.

Fresh, Compressive and Direct-Tensile characterization of Engineered Cementitious Composite

A new category of high-performance fiber-reinforced composite broadly known as Engineered Cementitious Composite (ECC) has gained rapid attention in the construction industry in recent years. The exceptional behaviour of ECC, therefore high ductility, toughness, and durability, make it a promising material for various structural applications such as tunnel inner lining, dam and bridge deck slab construction. This investigation aims to study the fresh and mechanical characteristics of ECC, including workability, compressive, and direct tensile strength. A total of 15 ECC mixes are prepared with varying superplasticiser-binder ratio (0.200, 0.225, 0.250, 0.275 and 0.300 %), sand-binder ratio (0.35, 0.40 and 0.45) and a constant water-binder ratio (0.27). The mini-slump cone test was performed to examine the workability of the fresh ECC mixtures. The results showed that using a higher content of the superplasticiser resulted in an upsurge in both the workability of the fresh ECC mixtures and the mechanical strength of ECC, particularly the tensile strength. Apart from this, both the mechanical tests are performed at the 7 and 28 days. As per the results, both the compressive strength and direct tensile strength of ECC are found to be comparatively higher than that of the conventional mix. In conclusion, ECC is an efficient construction material for various structural applications, especially for the latest 3D printing construction techniques. The uniform dispersion of fibers significantly improves the tensile strength and ductility of ECC, making it a suitable material for seismic-resistant structures.

Identification of key habitats and conservation threats of the Ganges River dolphin (Platanista gangetica) of Bangladesh

Ganges River Dolphins (Platanista gangetica) are known to inhabit all major river systems in Bangladesh. However, comprehensive spatial records for this globally endangered aquatic mammal are notably scarce nationwide. Furthermore, their habitats are increasingly threatened due to excessive utilization of aquatic resources and their habitats by the growing human population. To allocate limited resources in safeguarding high-priority dolphin habitats, we conducted field surveys and arranged stakeholder consultations to identify key dolphin habitats and the conservation threats they face across Bangladesh. Through this process, we have identified 14 river segments as high-priority winter habitats for Ganges River Dolphins. These dolphins encounter both direct and indirect threats within their habitats. Direct threats include entanglement and occasional intentional killing for traditional medicinal purposes and as fish attractants. Indirect threats leading to habitat degradation comprise the construction of dams and barrages for upstream water extraction, increasing industrial pollution in river waters, overfishing, and alterations to river morphology caused by siltation and sedimentation. The heavy reliance of local communities on dolphin habitats, coupled with a lack of widespread awareness and insufficient conservation efforts, pose significant challenges to the future survival of Ganges River Dolphins in Bangladesh. Bangladesh J. Zool. 51(3): 253-266, 2023

Economic Development Drives Massive Global Estuarine Loss in the Anthropocene

AbstractEstuaries have great ecological and economic value and sustain both population and economic growth. Global‐scale analyses suggest that human activities drive estuarine area change but these projections neglect direct human‐estuary interactions and socio‐economic feedbacks. Here, we quantified area changes of 2,396 estuaries in response to recent human impacts (e.g., land reclamation, estuarine dam construction) and economic development between 1984 and 2019, and find that estuarine area shrank by 5,372 km2 whereas upland submergence created 5,015 km2 of estuarine area elsewhere. Approximately 44% (n = 1,046) of today's estuaries have been directly altered through land reclamation, estuarine dam construction, or a combination of both, and ∼250,000 acres (1,027 km2) of estuarine area have been directly converted to urban or agricultural fields. Nearly 90% (923 km2) of land reclamation occurred in Asia linked to recent advances in economic development during the middle‐income stage. Additional historical mapping and 5‐year interval analyses revealed that while human alterations were insignificant during the low‐income stages, estuaries were predominantly altered during their middle‐income stages, where estuarine degradation is a common consequence of economic growth. However, this trend stabilizes in high‐income countries with the adaption of conservation laws and policies. Together, our results indicate that large‐scale estuarine loss can be avoided by preserving estuaries in low‐ and mid‐income countries in the early stages of economic development.